We propose to isolate stable thiiran-2-one 1, 1-dioxides and study the chemical reactions of these systems. New in situ cycloaddition reactions of the ketene-sulfur dioxide adduct are also being investigated. The biological activity of some of the products of these reactions will be tested. In addition, the cycloaddition reactions of substituted ketenes in liquid sulfur dioxide are being examined with particular emphasis on the mechanism of these reactions.